Negated vector store filters drop records without the property on the SQLite and Milvus stores #1780

What happens

Measured on main at ad8ff24 with nine records in one collection: five carry an integer property d_int (2, 1, -1, 0, and 3) and four do not carry it. Count of records each filter returns:

not (d_int = 2) on the SQLite stores and Milvus returns only the four records holding another value and drops the four without the property, so a filter and its negation together miss records. Qdrant returns all eight. The same split holds for string properties and for properties not in indexed_properties_schema. not (d_int in [1, 2]) drops the four on the SQLite stores and Milvus 2.6.24 and keeps them on Qdrant and Milvus Lite.

Why

• The SQL stores compile a leaf to and_(type_check, column <op> value) (packages/server/src/memmachine_server/common/filter/sql_filter_util.py:183-187) and Not to ~inner (:229-230). For a record without the property the leaf is SQL NULL, NOT NULL is NULL, and the row is filtered out. != compiles to column != value, which is NULL there as well.
• The Milvus store renders Not as Milvus not (...) and != as Milvus != over the property's dynamic field (packages/server/src/memmachine_server/common/vector_store/milvus_vector_store.py:116-119, :132-136); neither matches an entity that lacks the field.
• The Qdrant store renders both != and Not as must_not (packages/server/src/memmachine_server/common/vector_store/qdrant_vector_store.py:96-99, :150-157), which admits points without the field.

Expected

Negation is the complement on every store: not (f) matches exactly the records f does not match, records without the property included, and x != v matches the same records as not (x = v).

Fix

#1616 makes negation the complement on every backend: != parses as Not(Equals), and the SQL compilers render Not as NOT COALESCE(x, FALSE). For Milvus it builds on #1736, which pushes negation down to the conditions and admits entities lacking the property.

🤖 Written by Claude Code (Claude Opus 5.5) on behalf of @edwinyyyu.